1. Field of the Invention
The invention relates to an electric drive system, in particular for vehicles. Specifically, it is concerned with a drive system comprising two or more drive motors, at least one generator driven by a combustion machine, and one or more power electronics units associated with the drive motors and the generators, with the arrangement of drive motors, generator and power electronics units being controlled by a control means in accordance with the settings/operations of operating elements.
2. Description of the Related Art
Electric drive systems of this kind are known. The electric power demanded from the two or more drive motors has to be made available by the generator. In accordance with the power demanded, the combustion engine driving the generator has to be controlled and regulated. The power electronics unit associated with the generator converts the alternating voltage supplied from the generator into direct voltage. The output of the power electronics unit associated with the generator constitutes a direct-voltage intermediate circuit from which the power electronics units associated with the drive motors and acting as inverters, drain electric power.
The present invention is concerned with the problem of operational safety of such an electric drive system: in case of failure of the generator of such a drive system, this corresponds to an overall failure of the drive system. However, the situation is similar also in case of failure of one of the plurality of electric drive motors, at least when, in case of a track-laying vehicle, one drive motor drives one driving chain or track on one side of the vehicle and the other motor is in charge of the drive on the other side of the vehicle; for, in that event, the vehicle virtually would not be maneuverable any more.
To solve specifically the problem addressed hereinbefore, there has already a suggestion been made, namely to split generator and drive motors as well as power electronics units belonging to the drive motors into two or more partial units each and to provide a kind of “crossover connection” in the sense that, in case of splitting into two partial units each in a motor vehicle drive system having separate drives for the left-hand and right-hand vehicle sides, the two power units on the left-hand side feed a partial drive unit on the left-hand side and a partial drive unit on the right-hand side, with this applying to the other vehicle side in corresponding manner. The effect achieved thereby is that, for example, in case of a malfunction of a partial drive unit on one vehicle side, the still intact partial drive unit provided there is fed from a power unit of the other vehicle side, so that partial load operation of the vehicle is still possible by corresponding compensation measures. The generator may be connected to the power electronics units via separate circuits which in turn can each be fed by a generator of their own. The generator or generators have no power electronics unit of their own associated therewith.
With the solution in the form of a “crossover coupling” as described hereinbefore, the power units feeding the drive means are controlled by several control units via signal bus lines. The combinations of power units and motor units provided for the individual vehicle sides are accessible from the control means via the power units only. There is no unequivocal association of the drive motors with partial power units. In case of failure of a partial power unit on one vehicle side including the partial drive motor directly connected thereto, the associated partial power unit reacts by deactivating the partial drive motor on the other vehicle side that is coupled therewith. The “crossover coupling” thus indeed permits a rapid reaction of the partial power units in case of failure of the respective partial power units that are associated in pairs thereto, however, it is possible to still further develop the arrangement with respect to the possible flexibility thereof.